Refresh issue icons

[ashygee]

This adds refreshed issue icons

[laserlemon]

Out of curiosity, where did issue-in-progress go? We have a use case for it in our app. And issue-reopened seems to have been left out of the conversion from exclamations to dots. Was that intentional?

[Andre601]

I need to ask this: Why was issue-closed accepted? Will that be used on GitHub in the near future?
If so, why did it not receive some minor changes?

Right now is the issue-closed icon identical to the check-circle one.

I made this comparison here between the issue-closed and check-circle icons, by importing the 24px version of each at 500px scale into Gimp (So both are 500x500px dimension)

The left one is the check-circle and the right one the issue-closed icon and as you can see is there virtually no difference between both.

This is imo wasted storage space, since the check-circle could've just been used for closed issues imo.
Alternatively could the old issue icon be just updated with the dot to make it more unique.